Samuel N. Luoma Alan W. Decho 1991 <p>Time courses for ingestion, retention and release via feces of microbial food was investigated&nbsp;using 2 bivalves with different feeding strategies, <i>Potamocorbula amurensis</i> and <i>Macoma&nbsp;balthica</i>. The results showed 2 pathways for the uptake of food material in these clams. The first is&nbsp;represented by an initial label pulse in the feces. The second pathway operates over longer time&nbsp;periods. Inert ⁵¹Cr-labeled beads were used to determine time frames for these pathways. The first&nbsp;pathway, involving extracellular digestion and intestinal uptake, is relatively inefficient in the&nbsp;digestion of bacterial cells by <i>P. amurensis</i> but more efficient in <i>M. balthica</i>. The second pathway,&nbsp;involving intracellular digestion within the digestive gland of both clams, was highly efficient in&nbsp;absorbing &nbsp;bacterial carbon, and was responsible for most chromium uptake. Differences in the overall&nbsp;retention of microbial ⁵¹Cr and ¹⁴C relate not to gut-passage times but to the processing and release&nbsp;strategies of the food material by these 2 clams.</p> application/pdf en Inter Research Time-courses in the retention of food material in the bivalves <i>Potamocorbula amurensis</i> and <i>Macoma balthica</i> significance to the absorption of carbon and chromium article